This invention relates to an improvement in the preparation of readily soluble potassium silicate powders by spray drying. This improvement is realized when hydrophilic silanes are combined with the silicate solution to be spray dried.
The spray drying of sodium silicate solutions to provide free-flowing readily soluble powders is well known. U.S. Pat. Nos. 1,198,203 and 1,517,891 among others describe various equipment and methods involved in spray drying sodium silicate solutions. Various commercial products appear to be prepared by these or similar methods. Spray dried potassium silicate powders do not appear to be well known and patents directed to processes for preparing such products have not been found. U.S. Pat. No. 3,918,921 includes potassium silicate solutions among the solutions that may be spray dried in a special manner to provide agglomerated products. The examples of this patent do not show the processing of potassium silicate solutions; the use of a mixed sodium-potassium silicate solution is illustrated.
It appears that partially dried potassium silicate solids are distinctly more adherent than corresponding sodium silicate materials. This property prevents efficient production of potassium silicate powders on equipment generally used for spray drying sodium silicate powders. The spray tower becomes so coated with tacky solids that production of potassium silicate is impossible.
It is an object of this invention to provide a process improvement that allows efficient production of potassium silicate powders by spray drying the corrosponding solutions.